IACM-Bulletin of November 24, 2002

Science — Cannabis may be helpful in Parkinson's disease

Nearly half of Parkinson's disease patients who have tried cannabis say the drug helped relieve their symptoms, according to a patients' survey. Dr. Evzin Ruzicka, neurologist at Charles University in Prague (Czech Republic), reported the findings at the Movement Disorders Society's Seventh International Congress of Parkinson's Disease and Movement Disorders held on 10-14 November in Miami (USA).

The investigators asked all patients who were treated for Parkinson's disease at a centre in Prague to complete a questionnaire that asked about cannabis use and about several Parkinson's disease symptoms. Of 630 questionnaires sent out 339 (54%) were returned. Among the responders, 25% reported that they had used cannabis. Most had used it orally, either as fresh or dried leaves.

Within this group, 39 patients (46%) reported that their Parkinson's disease symptoms in general were relieved after they started using cannabis. 26 (31%) reported an improvement in tremor while at rest, and 38 (45%) experienced a relief of bradykinesia. Relief of muscle rigidity was reported by 32 (38%), and 12 (14%) said they had an improvement in levodopa-induced dyskinesias. The respondents reported that the improvement in symptoms occurred an average of 1.7 months after they had started using cannabis. Patients who used it for at least three months were more likely to experience symptom relief than those with shorter experience.

(Source: Reuters Health of 13 November 2002)

UK — British Lung Foundation warns against cannabis smoking

A report on the risks of cannabis smoking issued by the British Lung Foundation attracted some media resonance. The report comes to similar conclusions as previous reviews of the available studies.

It says, that the concentrations of known cancer causing agents "are up to 50% higher in the smoke of a cannabis cigarette" compared to the smoke of tobacco cigarettes, that smoking a cannabis cigarette results "in fourfold greater amount of tar inhaled," due to longer breath holding and other factors, and that "3-4 cannabis cigarettes a day are associated with the same evidence of acute and chronic bronchitis and the same degree of damage to the bronchial mucosa as 20 or more tobacco cigarettes a day."

The report notes that "research linking cannabis smoking to the development of respiratory cancer exists although there have also been conflicting findings" and that the evidence concerning "a possible link between cannabis smoking and Chronic Obstructive Pulmonary Disease (COPD) has not yet been conclusively established." COPD includes diseases such as chronic bronchitis and emphysema.

It says, that cannabis of today might be more dangerous compared to cannabis 30 years ago since it contains higher amounts of THC. However, the report does not mention that higher THC contents allow to smoke less cannabis to get the same effect, which is advantageous with regard to possible damage to the respiratory tract.

The report warns from cannabis smoking against asthma while conceding that cannabis may also be taken orally without any damage to the lungs, but stating that "oral intake of THC has also shown to cause unwanted side-effects," - which is, however, true for every asthma drug.

(Sources: British Lung Foundation. A smoking gun. Available at:

http://www.lunguk.org/news/a_smoking_gun.pdf, PA News of 10 November 2002, Reuters of 11 November 2002)

Science — Cannabis use and mental disorders

It is established that persons with mental disorders such as schizophrenia, anxiety and depression have a higher rate of tobacco use, cannabis use and alcohol dependence. Additionally, causal relationships to these disorders have been proposed for alcohol dependency and cannabis use. Three studies published in the British Medical Journal support the assumption of a causal relationship between cannabis use and mental illnesses, at least in young users of the drug.

An Australian study with 1,601 pupils found that teen-age girls who were daily cannabis users were five times more likely to suffer from later depression and anxiety than other adolescents, while there was no increased risk for male teenagers.

In a study of 1,037 people born in New Zealand between 1972-73, those who began using cannabis by age 15 were four times more likely to suffer "schizophreniform disorders" - but not schizophrenia - at the age of 26 than adolescents who did not use the drug. After psychotic symptoms at age 11 were controlled for, the still slightly increased risk was non longer significant, suggesting that teenagers already at greater risk of later developing mental health problems are also more likely to smoke cannabis. In contrary to the Australian study the New Zealand study did not find an association between cannabis use at age 15 and later depressive disorder.

Another study of 50,087 Swedish men aged 18 to 20 showed the use of cannabis increased the risk of schizophrenia within the next 15 years by 30 percent, and that the risk increased with increased intensity of use. Of 1,648 subjects who had used cannabis 18 (1.1%) developed schizophrenia. Of 70 subjects who used the drug more than 50 times 4 (5.7%) developed schizophrenia.

In an invited comment Dr. Joseph Rey and Dr. Christopher Tennant of the University of Sydney stated in the same journal that these and other findings "strengthen the argument that use of cannabis increases the risk of schizophrenia and depression", but that it is still unclear "whether the use of cannabis triggers the onset of schizophrenia or depression in otherwise vulnerable people or whether it actually causes these conditions in non-predisposed people."

(Source: British Medical Journal of 23 November 2002 at: www.bmj.com)

News in brief

Science — Journal of Cannabis Therapeutics

The new issue of the Journal of Cannabis Therapeutics, volume 2(3/4), has been published. Please find the abstracts of all articles and the complete text of an extensive historical review on cannabis treatments in obstetrics and gynaecology by Dr. Ethan Russo at >www.cannabis-med.org/science/jcant.htm<.

Spain — Meeting of the SEIC

The Sociedad Española de Investigación sobre Cannabinoides (Spanish Society on the Investigation of Cannabinoids) held its third annual meeting on 15-16 November in Malaga. More at: >http://www.ucm.es/info/seic-web<.

Slovenia — Conference on medical use

A conference on the medical use of cannabis was held on 18 November in the General Hospital of Ljubljana organised by the Government Office for Drugs. Speakers were Willem Scholten, William Notcutt, Brendan Hughes and Henrie Korthout.

Science — Cannabis and cognition

Very heavy use of cannabis may be associated with persistent decline in cognitive performance. Participants were divided according to weekly smoked cannabis cigarettes into light users (2-14 joints, mean: 11), middle users (18-70 joints, mean: 42) and heavy users (78-117 joints, mean: 94). After 28 days of abstinence participants performed a number of neurocognitive tests. Very heavy users performed significantly worse on 5 of the 35 tests compared to light users, suggesting irreversible effects. Memory, executive functioning, psychomotor speed, and manual dexterity were affected. (Source: Bolla KI, et al. Neurology 2002 Nov 12;59(9):1337-43)

Science — Cannabis and psychosis

Cannabis use was not associated with development of psychosis in a very high-risk group. 100 young people identified by the presence of subthreshold psychotic symptoms, or a combination of first-degree relative with a psychotic disorder and recent functional decline were followed for a 12-month period. 32% developed an acute psychotic episode. The risk was not associated with the level of cannabis use prior to enrolment in the study. Authors conclude that the results suggest that cannabis use may not play a relevant role in the development of psychosis in a high-risk group for the disease. (Source: Phillips LJ, et al. Aust N Z J Psychiatry 2002 Dec;36(6):800-6.)